What are the clinical features, presentation, and management of a middle cerebral artery (MCA) stroke?

Middle Cerebral Artery Stroke: Clinical Syndromes and Neurologic Findings

MCA stroke presents with contralateral hemiparesis, sensory loss, homonymous hemianopsia, and aphasia (if dominant hemisphere) or neglect (if non-dominant hemisphere), with early CT signs detectable in up to 82-94% of cases within 6 hours. 1, 2

Clinical Presentation by Hemisphere

Right MCA Territory (Non-Dominant Hemisphere)

• Left-sided weakness affecting face, arm, and leg (arm typically more affected than leg) 1
• Left-sided paresthesia or sensory loss 1
• Left-sided neglect (inattention to left side of space) 1
• Abnormal visual-spatial ability 1
• Right homonymous hemianopsia (loss of right visual field in both eyes) 1
• Monocular blindness affecting the right eye (if internal carotid artery involvement) 1

Left MCA Territory (Dominant Hemisphere)

• Right-sided weakness affecting face, arm, and leg 1
• Right-sided paresthesia or sensory loss 1
• Aphasia (expressive, receptive, or global depending on location) 1
• Left homonymous hemianopsia 1
• Monocular blindness affecting the left eye (if internal carotid artery involvement) 1

Specific Neurologic Examination Findings

Motor Deficits

• Contralateral hemiparesis with characteristic arm > leg pattern (cortical involvement) 1
• Gaze deviation toward the side of the lesion (away from the weak side) 3
• Facial droop on the contralateral side 1

Sensory Deficits

• Contralateral hemisensory loss affecting all modalities 1
• Loss of cortical sensory functions (stereognosis, graphesthesia, two-point discrimination) 1

Higher Cortical Signs

• Aphasia types (Broca's, Wernicke's, or global) in dominant hemisphere strokes 1, 3
• Neglect syndrome in non-dominant hemisphere strokes 1
• Apraxia (inability to perform learned motor tasks) 1

Early CT Signs (Within 6 Hours)

Direct Arterial Signs

• Hyperdense MCA sign: Visible thrombus or embolus in the proximal MCA appearing as increased density on non-contrast CT 1, 4, 5
• This sign indicates acute arterial occlusion and is never found in isolation—always associated with parenchymal changes in extended infarcts 5

Parenchymal Signs (Detectable in 82-94% of Cases)

• Loss of gray-white matter differentiation at the cortical ribbon, particularly at lateral margins of the insula 1, 2
• Attenuation of the lentiform nucleus (loss of normal density of basal ganglia structures) 1, 2, 5
• Loss of the insular ribbon (obscuration of the insular cortex) 1, 2, 5
• Sulcal effacement (compression of CSF spaces indicating early edema) 1, 2, 5

Prognostic CT Patterns

• Involvement of >1/3 MCA territory is associated with poor outcomes and increased hemorrhagic transformation risk (8-fold increase with rtPA) 1, 2
• Presence of two or three parenchymal signs (attenuation of lentiform nucleus, loss of insular ribbon, or sulcal effacement) predicts extended MCA infarct and poor outcome 5
• Early mass effect or edema within 3 hours carries 8-fold increased risk of symptomatic hemorrhage after thrombolysis 2

Clinical Predictors of Malignant Course

Early Warning Signs (Within Hours)

• Severe hemiparesis at presentation 3
• Gaze deviation 3
• Higher cortical signs (aphasia, neglect) 3

Progressive Signs (Days 1-7)

• Headache 3
• Vomiting 3
• Papilledema 3
• Reduced consciousness progressing to coma 3

Anatomic Localization Patterns

Proximal M1 MCA Occlusion

• Combined mechanism most common (54.1% of cases) 6
• Larger territory involvement including both cortical and deep structures 6
• Higher baseline stroke severity 7
• More basal ganglia involvement 7

Distal M1/Proximal M2 MCA Occlusion

• Artery-to-artery embolism/hemodynamic infarction most common (46.2%) 6
• More cortical involvement with relative sparing of deep structures 7
• Better collateral supply associated with smaller infarct volumes 7

Critical Pitfalls to Avoid

• Normal early CT does not exclude acute ischemic stroke—clinical assessment remains paramount, as CT shows abnormalities in <50% of patients in the first hours with standard sequences 1, 2
• Physician accuracy in detecting >1/3 MCA territory involvement is only 70-80%—reliability is variable and reproducibility is limited 1, 2
• CT is relatively insensitive for small cortical/subcortical lesions, especially in the posterior fossa 1, 2
• Time of onset is defined as when patient was last known to be symptom-free—for wake-up strokes, this is when they went to sleep, not when they awoke 1
• Do not delay thrombolytic therapy to obtain advanced imaging beyond non-contrast CT if the patient is otherwise eligible 2